I'd be really interested to hear what effect this has on revenue.
According to Google Analytics one of my high-volume sites is just over 25% mobile users now (although another site is under 2%). I don't do anything special for mobile yet (the site is very simple), but as the pages/visitor are much lower for mobile I probably should.
Interestingly the main "carriers' showing up for mobile for me are (Time Warner) Roadrunner and Comcast, which implies a lot of mobile usage is tethered to wi-fi at home. iPhone, iPod and iPad dominate, but Android is catching up.